On Sun, Mar 22, 2009 at 04:16:37PM -0700, Arjan van de Ven wrote:

On Sun, 22 Mar 2009 16:03:31 -0700
"Paul E. McKenney" [off-list ref] wrote:

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On Sun, Mar 22, 2009 at 03:44:33PM -0700, Arjan van de Ven wrote:

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On Sun, 22 Mar 2009 13:52:12 -0700
"Paul E. McKenney" [off-list ref] wrote:

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On Sun, Mar 22, 2009 at 12:46:32PM -0700, Arjan van de Ven wrote:

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On Sun, 22 Mar 2009 09:53:24 -0700
"Paul E. McKenney" [off-list ref] wrote:

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How many synchronize_rcu() calls are you seeing on the
boot path?

I see 20 that hit the above code path (eg ones that wait)
until userspace starts.

So with well-behaved readers, the full sequence would be worth
something like 50-60 milliseconds.

yeah it's about 10% if the total kernel boot time.. so it does
start to matter

Half-second boot, eh?  That would indeed be impressive.

half a second until calling init.. that's what I have today (with
all drivers built in).. nothing really special needed for it
(well a few small patches that are pending for 2.6.30 ;-)

I thought the measurement was until the desktop was running with no
more disk activity.  ;-)

yeah that's like 2 seconds after that ;)

I must confess that I still dream of it booting faster than I perceive.
Of course, this is becoming ever easier to achieve as I continue to
grow older...  ;-)

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But in any case, I will see what I can do about speeding up
synchronize_rcu().  I will likely start with TREE_RCU, and I may need
some sort of indication that boot is in progress.

system_state == SYSTEM_BOOTING is not a very elegant test but it works

Fair enough...  This would be until init, correct?

							Thanx, Paul